Router stats and actual performance very different

Just got a new "Up to 8Mbps" ADSL connection with BT Broadband and one of their Voyager 2200V routers. The performance is poor. Speedtest from this site shows download as about 0.2 Mbps and that's how it feels. However, the router stats show 4+Mbps.

What might cause the difference between the router stats, which look reasonable, and the actual performance, which is so poor please? TIA, Mick W.

How about the 10-day training period if you've only just got your connection.

Leave it 10 days, allow the line to train in and then see what speeds you get.

OK, thanks. It's been 7 days so far. I'll give it another 7 and see what happens.

Thank you.

In reply to:

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However, the router stats show 4+Mbps.

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Do you mean synch speed? Additionally, it may be useful to post your linestats [Noise Margin and Attenuation]].

Thanks. Here are the details.

Line Rate
Down 4256 Kbps
Up 448 Kbps

Noise Margin
Down 5.9 dB
Up 20.0 dB

Line Attenuation
Down 15.5 dB
Up 31.5 dB

Output Power
Down 18.9 dBm
Up 11.9 dBm

OK, synch speed is 4Mbit/s, which equates to 400kByte/s [an area of possible confusion]. It looks fair for your stats, though maybe someone more used to max may say you ought to be getting more. But I don't think that is the problem

To yuor original question:

In reply to:

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What might cause the difference between the router stats, which look reasonable, and the actual performance, which is so poor please?

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Congestion on shared parts of the network, or throttling by your ISP - or MTU problems on your part, or problems with your wirelss or running other internet activity whiledoing the speedtest.

Congestion on shared parts of the network, or throttling by your ISP - or MTU problems on your part, or problems with your wirelss or running other internet activity whiledoing the speedtest.

Thanks. I'm sure that nopthing else is going on on the network. Im not using wireless. I wasn't doing anything else at the time of running speedtest (and I ran it several times to compare).

So, that leaves MTU problems or throttling. I think I'll leave it another week to see if the training has any affect and then contact the ISP.

Thanks for your help.

Your line speed (if maintained) will give you an IP Profile of 3500 kb/s. Actual throughput will be somewhat less that that - with a fair wind about 2900 kb/s.

In this situation best to use www.speedtester.bt.com, which gives you a figure for IP Profile as well as the download speed. Slight problem, it tends to be very busy this time of day and sends you away, or diverts you to an older one that doesn't give the profile. Better during the morning.

The IP Profile is what actually decides your maximum speed. At 4000+sync it should be 3.5Mb probably. See this table. If it is much lower, then you have had a very low sync in the last 3 days, and it should go back up.